Vaporizing apparatus



21, 1965 R. A. SCHMIDT ETAL 3,224,577

VAPORIZINGv APPARATUS Original Filed April 27, 1962 r i l i 4 4 LA-:4

Ill

III

7 INVENTORS Ray 6. Scfimfat BY Gearge 6! A Wdl/dc ATTORNEYS 3,224,677 VAPURIZING APPARATUS Roy A. Schmidt, Mill Neck, N.Y., and George A. P.

Wallace, Greenwich, Conn., assignors to Kelroy Corp.,

Long Island City, N.Y., a corporation of New York Continuation of application Ser. No. 190,708, Apr. 27, 1962. This application Sept. 14, 1964, Ser. No. 398,828

1 Claim. (Cl. 239-401) This application is a continuation of application Serial No. 190,708 filed April 27, 1962, now abandoned.

This invention relates to improvements in spray guns or Vaporizers of the type used for converting liquid materials such as water, paints or other coating substances, insecticides, deodorants etc. to fine mist-like sprays. Such devices ordinarily operate by interaction between a jet of the liquid to be vaporized and a jet of gas, for example, air, discharged under pressure in a path that intersects or interferes with the liquid jet, breaking it up into a cloud of microscopic droplets and propelling the cloud as a spray of the desired configuration.

Some of the problems encountered in prior art spray guns are:

(a) Fouling or clogging of the nozzle by accumulation of dried solidified components of the liquid being sprayed.

(b) Erratic operation, particularly at low flow rates.

Diificulty of precise control in adjustment of flow rate and in shut-off.

The principal object of the present invention is to provide an improved type of spray gun or vaporizer wherein the foregoing problems are avoided. More specifically, it is an object to provide spray guns in which all internal parts in contact with the fluid remain so when the gun is shut off, as well as when it is spraying. This prevents drying or evaporation of the liquid and formation of deposits on the internal parts.

Another object is to prevent formation of bubbles or foam in the exit orifice of the nozzle, to insure uniformity of fiow of the liquid into the spray.

Other objects are the provision of abrupt, dripless shutoff, convenient precise adjustment of flow rate, and economical consumption of the compressed gas.

Briefly, the above objects are achieved by maintaining the liquid and gas flow paths separate within the gun, by placing the liquid flow control valve at the extreme exit end of the liquid passage in the nozzle, and by providing a rapid vibratory motion of the closure element of the liquid control valve during operation. In a preferred embodiment of the invention, the liquid control valve is actuated by a vibratory electric motor arranged to cyclically open and close the valve when energized, and to allow spring 51 to abruptly close the valve when de-energized.

The invention will be described with reference to the accompanying drawing, the single figure of which shows a longitudinal cross section of a presently preferred embodiment of the invention.

The gun shown in the drawing includes a head portion 1 provided with entrances 3 and- 5 connected to external fittings 7 and 9 for the admission, respectively, of compressed gas and the liquid to be sprayed. The fitting 9 contains a filter cartridge 10 for removal of any foreign matter from the liquid. The fluid entrance 5 is connected to a generally cylindrical passage 11 extending along the longitudinal axis of the gun. A tip assembly or nozzle 13 is secured in the passage 11 and extends outward therefrom, terminating in an orifice 15. The nozzle 13 is also provided with gas passages 17, which are connected by way of a passage 19 in the head 1 to the gas inlet 3. The gas passages 17 terminate in a chamber 22 surrounding the fluid exit portion of the tip and provided with an opening 21 through which the end ited States Patent 0 0f the fluid exit passes. This arrangement provides for the formation of a hollow cylindrical air or gas jet closely surrounding the fluid jet at the exit point.

The interior of the fluid passage in the tip of the nozzle is provided with a valve seat 23 preferably resilient and made of nylon or similarly inert plastic material and shaped to cooperate with the tapered portion 25 of a needle valve closure member. The needle valve formed by members 23 and 25 is placed close to the liquid exit orifice 15, and is provided with a stem 27, which extends longitudinally of the fluid passage through an opening 29 into the interior of a hollow housing 31 attached to the lower end of the head member 1.

The lower end of the housing 31 is internally threaded for engagement with a threaded plug 33, which is provided with manually rotatable knob 35 for adjustment of the position of the plug 33 longitudinally within the housing 31. The internal surface of the plug 33 supports a centrally located post 37, which in turn supports the outer shell of an actuator 39. To provide for rotation of the post 37 with respect to the shell 39, and to accommodate minor misalignments, the post 37 engages the shell 39 with a bearing surface arrangement 41.

In the illustrated embodiment of the invention, the actuator 39 is an electromagnetic motor of the solenoid type, comprising an electromagnet Winding 43 surrounding a relatively movable cylindrical ferromagnetic armature 45. The shell 39 is also made of ferromagnetic material, and is provided with an opening at its upper end to permit reciprocating movement of the armature 45.

The upper end of the armature 45 is secured to the lower end of the valve stem 27 as by means of a pin 47. The pin 47 also acts to restrain a washer 49 surrounding the upper portion of the armature 45 and confining a compression spring 51 against the upper end of the shell 39 of the actuator. A second compression spring 53 surrounds the spring 51 and extends between the actuator shell 39 and the head member 1 to hold the body of the actuator firmly against the supporting post 37.

The electromagnet 43 is connected by way of leads 55 in conventional manner to an ordinary electric power cable, not shown, for connection to a cycle A.-C. power supply. A manually operable switch, also not shown, may be included in the electrical connection to the magnet 4-3 and secured to the housing 31 in any conventional arrangement.

A passage 20 extends from the gas entrance 3 to the interior of the housing 31, and a small opening 34 in the housing allows some of the propellant gas to flow through the housing for cooling the actuator motor.

The adjustable plug 33 is provided with a locking arrangement such as a screw 57 and a slot 59 out part way across the plug. The knob 35 is secured to the lower portion of the plug 33 by a set screw 61, and carries a fiducial mark 63 cooperating with a scale 65 on the lower end of the housing 31.

In the operation of the described gun, the liquid to be sprayed is applied to the fitting 9 under a pressure of from one-half to ten pounds per square inch. The pressure is not critical, but as a general rule should be relatively low for liquids of low viscosity and higher for liquids of high viscosity. Air or other propellant gas is applied to the fitting 7 at a pressure within the range of ten to one hundred pounds per square inch. The gas supply, and preferably also the liquid supply, should inclucle suitable known means for regulation and adjustment of the pressure.

The magnet 43 is energized from an alternating current source such as the usual A.C. lines. With the electric, gas and liquid supplies all connected, the lock screw 57 is loosened and the knob 35 rotated to move the actuator body 39, and with it the valve stem 27, upward to the point Where the valve 23, 25 is completely closed and no liquid discharges from the nozzle. In this position the actuator is blocked and will not vibrate, although energized. The indicator set screw 61 is then loosened to permit adjustment of the indicator 63 to zero on the scale 65, and resecured.

After the above described zero setting adjustment has been made, the knob 35 is adjusted to establish the desired flow rate. Typically, the flow rate may be anywhere in a range of from less than one cubic centimeter of liquid per minute, up to more than one pint per minute.

Liquids under pressure usually contain gases, e.g. air or volatile solvent components, which emerge as expanding bubbles when the pressure is reduced to atmospheric. This phenomenon tends to cause foaming at the nozzle and non-uniform liquid flow rate, patricularly when the flow rate is low. The above described vibratory operation of the liquid control valve in accordance with this invention breaks up the bubbles to form much smaller ones which can pass smoothly through the nozzle orfice without causing perceptible random variations in flow rate.

Owing to the use of alternating eurernt for energization of the actuator motor, the valve stem 27 is alternately withdrawn from its closed position by the armature 45 and pushed toward its closed position by the compression spring 51 at a rate of 120 times per second in the case of a 60 cycle electric power supply, and that the motion continues throughout each duty cycle of the spray gun. Such rate is in the very low audio range so that cavitation and other special effects of high or ultrasonic frequency are not involved. It will be understood that the stem can be reciprocated at a still lower rate by energizing the actuator only on the positive or negative halves of the energizing source, as by the use of a conventional half-wave rectifier. The length of the stroke, and hence the average or effective opening of the needle valve 23, 25 depends upon the position of the actuator body 39 as fixed by adjustment of the plug 33.

It will be apparent from the foregoing that the several objects of the invention are fulfilled by the described embodiment thereof. Although a particular preferred arrangement i disclosed in detail, it will be understood that many variations are possible within the spirit of the invention. For example, the vibrating actuator could be of a known pneumatically operated type, energized from the propellant gas supply. The liquid control valve may be, for certain applications, constructed for example like a poppet valve or other arrangement adapted to be operated in a vibratory fashion.

We claim:

A spray gun including a body member, a nozzle on said body member provided with a generally central passage for the flow of a liquid to be atomized, a conically tapered valve seat in said passage adjacent the exit end thereof, a closure member tapered to cooperate as a needle valve with said valve seat, said closure member being provided with a stem extending through said passage, an actuator comprising two parts relatively movable toward and away from each other as said actuator is energized and de-energized to provide substantially rectilinear relative motion between said parts, and means reacting between the two parts of the actuator and biasing one of said actuator parts toward its extended condition; means connecting one of said actuator parts to said stem and adjustable control means to connect the other of said actuator parts to said body member for movement relative thereto in the direction of needle valve movement to control flow rate, said actuator being adapted to be energized in a pulsating manner to produce longitudinal vibrating motion of said stern and cyclically open and close said needle valve in vibratory movement in said passage a plurality of times for each duty cycle of the spray gun, said adjustable control means being movable to seat said needle valve against the force of the energized actuator, said adjustable control means connecting said other actuator part to the body member including an adjusting knob threaded into said body member and engaging said other actuator part in the direction of travel, and resilient means reacting between the body member and said other actuator part urging the latter toward said adjusting knob.

References Cited by the Examiner UNITED STATES PATENTS 1,323,778 12/1919 Lemp 239-585 1,627,727 5/1927 Charter 239585 2,481,620 9/1949 Rosenthal 2394 EVERETT W. KIRBY, Primary Examiner. 

